At present, the traditional optometry instruments have a large volume, and are not portable. And, it requires the user have certain professional knowledge, or it needs the professional optometrist to measure the visual acuity of the subject, and the subject cannot independently complete the visual acuity measurement. The working principle of traditional optometry instrument is: the subject fixes the fixed optotype inside (or outside) the instrument, and the measurement crew operates the three-dimensional joystick of the optometer, adjusts the three-dimensional distance between the optometer and the human eye to make the human eye in the working position of the optometry system, and then measures the visual acuity, the chin and forehead of the subject must be close to the measuring bracket tightly during operation. For those who do not cooperate with the measurement, or the measurer does not have enough professional skills, it results in inaccurate actual measurement results, which directly affect the accuracy of vision correction when configuring glasses.